Image sensing apparatus

ABSTRACT

An image sensing apparatus having a large depth of focus (DOF) and being compact in size is provided. The image sensing apparatus includes a plurality of light sources that shines light beams on an illumination portion of a document; a first mirror that receives incident light scattered by reflection from the document, to reflect the scattered light in the secondary scan direction; a plurality of first concaved aspheric mirrors that collimates light beams from the first mirror, to reflect therefrom the collimated light beams as substantially collimated light fluxes; an aperture mirror that reflects therefrom the light beams from the respective first aspheric mirrors, through apertures each having a light-shielded portion formed therearound and selectively passing the light beams therethrough; a plurality of second concaved aspheric mirrors that receives the light beams incident from the respective aperture mirror, to reflect the incident light beams as converging light beams; a second mirror that reflects the light beams in a direction perpendicular to the surface of the document, disposed on a path of the light beams to be converged by means of the second aspheric mirrors; a plurality of light receivers each having a light-receiving area that receives the light beams from the second mirrors, to form images according to the light beams from the respective apertures; and a casing where the first and second aspheric mirrors are disposed on a first side of the casing in the secondary scan direction, and the aperture mirror is disposed on a second side thereof in the secondary scan direction.

FIELD OF THE INVENTION

The present invention relates to image sensing apparatuses that are usedfor image sensing or identification devices such as photocopiers orfinancial terminals, respectively.

BACKGROUND OF THE INVENTION

For example, Japanese Unexamined Patent Publication H11-8742 (FIG. 2)discloses a sensing apparatus that utilizes a mirror array, as an imagesensing apparatus that senses image information.

In addition, Japanese Unexamined Patent Publication 2003-331267 (seeFIG. 2) discloses an image sensing device having a telecentric opticalsystem and an illumination system that are suited to test on one-timeprimary scanning of a plurality of testing portions being present on amounting substrate.

Furthermore, Japanese Unexamined Patent Publication H5-328024 disclosesthat an image sensing apparatus includes a light source lamp 24 thatshines light beams on a sensing object G; optical means 20 and 30 fortransmitting light beams reflected by the sensing object G; an opticalelement 44 for dividing the light beams from the optical means 20 and30, into a plurality of light fluxes each spaced apart a predetermineddistance; and a plurality of detectors 46 r, 46 g and 46 b provided withdifferent color filters, at a position where each of the light beamsdivided by the optical element 44 is received.

In the image sensing apparatus as set forth in Japanese UnexaminedPatent Publication H11-8742, the mirror array in an optical path from adocument 10 to a photo-sensor array 15 is configured to determineinclination of the optical axis of a first and a second mirror array sothat an axis perpendicular to the sensing surface of a document sensingsection may be in parallel with an axis perpendicular to alight-receiving surface of the photosensor array; however, no detaileddescription is disclosed regarding the mirror array's specific locationand the optical axis inclination.

The image sensing apparatus as set forth in Japanese Unexamined PatentPublication 2003-331267, including an epi-illumination light source 1and a side-illumination light source 4, are constituted by a first lens9 composed of a cylindrical lens and a second lens 7 of the image-takingsystem; and the first lens 9 is located within 50 mm apart from the testsubstrate, and the posterior focal point of the first lens 9 is made tocoincide with the incident pupil position of the second lens 7, therebyachieving a compact and telecentric optical system; however, no detaileddescription is disclosed regarding their specific locations and a scanmethod.

Furthermore, a problem has been that in the apparatus as disclosed inJapanese Unexamined Patent Publication H5-328024, there is a need for afocusing optical element 42 that makes variable a focusing distance forconverting red-blue-green (RGB) image information into electricalsignals using a three-line CCD (charge-coupled device) sensor array 46,thus resulting in a complex configuration.

The present invention is directed to overcome the foregoing issues, andan object of the present invention is to provide an image sensingapparatus having a large depth of focus and being compact in size.

SUMMARY OF THE INVENTION

In one aspect according to the present invention, an image sensingapparatus comprises a light source that shines light on an illuminationportion of a document across the entire range in a direction along alongitudinal axis of the apparatus (hereinafter referred to as primaryscan direction); a first mirror that receives incident light scatteredby reflection from the document, to reflect the scattered light in adirection along a transverse axis of the apparatus (hereinafter referredto as secondary scan direction); a plurality of first concaved asphericmirrors that collimates the light beams from the first mirror, toreflect therefrom the collimated light beams as substantially collimatedlight fluxes; an aperture mirror that reflects therefrom the light beamsfrom the first aspheric mirrors, through apertures each having alight-shielded portion formed therearound and selectively passing thelight beams therethrough; a plurality of second concaved asphericmirrors that receives the light beams incident from the aperture mirror,to reflect the incident light beams as converging light beams; a secondmirror that reflects the light beams in a direction perpendicular to thesurface of the document, disposed on a path of the light beams to beconverged by means of the respective second aspheric mirrors; aplurality of light receivers each having a light receiving area wherethe light beams from the second mirrors are incident, and images arethereby formed according to the light beams from the respectiveapertures; and a casing where at least the first and second asphericmirrors are disposed on a first side of the casing in a secondary scandirection, and the aperture mirror is disposed on a second side thereofin the secondary scan direction.

In another aspect according to the present invention, an image sensingapparatus comprises a light source that shine light on an illuminationportion of a document across the entire range in the primary scandirection, a first mirror that receives incident light scattered byreflection from the document, to reflect the scattered light in thesecondary scan direction; a plurality of first concaved aspheric mirrorsthat collimate the light beams from the first mirror, to reflecttherefrom the collimated light beams as substantially collimated lightfluxes; an aperture mirror that reflects therefrom the light beams fromthe first aspheric mirrors, through apertures each having alight-shielded portion formed therearound and selectively passing thelight beam therethrough; a plurality of second concaved aspheric mirrorsthat receive the light beams incident from the aperture mirror, toreflect the incident light beams as converging light beams; a secondmirror that reflects the light beams in a direction perpendicular to thesurface of the document, disposed on a path of the light beams to beconverged by means of the respective second aspheric mirrors; aplurality of light receivers each having a light receiving area wherethe light beams are incident from the second mirror and images arethereby formed according to the light beam from the aperture; and acasing where at least the first and second aspheric mirrors are arrangedin an array on a first side of the casing in the secondary scandirection, along the primary scan direction, and the apertures and theaperture mirror are arranged in respective arrays on a second sidethereof in the secondary scan direction, therealong.

In yet another aspect according to the present invention, the imagesensing apparatus comprises an RGB light source that shines light on anillumination portion of a document across the entire range in a primaryscan direction; a first mirror that receives incident light scattered byreflection from the document, to reflect the scattered light in asecondary scan direction; a plurality of first concaved aspheric mirrorsthat collimates light beams from the first mirrors, to reflect therefromthe collimated light beams as substantially collimated light fluxes; anaperture mirror that reflects therefrom the light beams from the firstaspheric mirrors, through apertures each having a light-shielded portionformed therearound and selectively passing the light beam therethrough;a plurality of second concaved aspheric mirrors that receives lightbeams incident from the aperture mirror, to reflect the incident lightbeams as converging light beams; a second mirror that reflects the lightbeams in a direction perpendicular to the surface of the document,disposed on a path of the light beams to be converged by means of therespective second aspheric mirrors; a plurality of light receivers eachhaving RGB filters corresponding to the respective optical wavelengthsof the RGB light beams in a light-receiving area where the light beamsfrom the second mirrors are incident and images are thereby formedaccording to the light beams from the respective apertures; and a casingwhere at least the first and second aspheric mirrors are disposed on afirst side of the casing in the secondary scan direction and theaperture mirror is disposed on a second side thereof in the secondaryscan direction.

In yet another aspect according to the present invention, an imagesensing apparatus comprises an RGB light source that shines light on anillumination portion of a document across the entire range in a primaryscan direction; a first mirror that receives incident light scattered byreflection from the document, to reflect the scattered light in asecondary scan direction; a plurality of first concaved aspheric mirrorsthat collimates light beams from the first mirrors, to reflect therefromthe collimated light beams as substantially collimated light fluxes; anaperture mirror that reflects therefrom the light beams from the firstaspheric mirrors, through apertures each having a light-shielded portionformed therearound and selectively passing the light beams therethrough;a plurality of second concaved aspheric mirrors that receives lightbeams incident from the aperture mirror, to reflect the incident lightbeams as converging light beams; a second mirror that reflects the lightbeams in a direction perpendicular to the surface of the document,disposed on a path of the light beams to be converged by means of therespective second aspheric mirrors; a plurality of light receivers eachhaving RGB filters corresponding to the respective optical wavelengthsof the RGB light beams in a light receiving area where the light beamsfrom the second mirrors are incident and images are thereby formedaccording to the light beams from the respective apertures; and a casingwhere at least the first and second aspheric mirrors are arranged inrespective arrays on a first side of the casing in the secondary scandirection, along the primary scan direction, and the aperture mirror isarranged in respective arrays on a second side thereof in the secondaryscan direction, therealong.

In still another aspect according to the present invention, an imagesensing apparatus comprises a fluorescent light source that shinesfluorescent light on an illumination portion of a document across theentire range in a primary scan direction; a first mirror that receivesincident light scattered by reflection from the document, to reflect thescattered light in a secondary scan direction; a plurality of firstconcaved aspheric mirrors that collimates light beams from the firstmirrors, to reflect therefrom the collimated light beams assubstantially collimated light fluxes; an aperture mirror that reflectsthe light beams from the first aspheric mirrors, through apertures eachhaving a light-shielded portion formed therearound and selectivelypassing the light beams therethrough; a plurality of second concavedaspheric mirrors that receives the light beams incident from theaperture mirror, to reflect the incident light beams as converging lightbeams; a second mirror that reflects the light beams in a directionperpendicular to the surface of the document, disposed on a path of thelight beams to be converged by means of the respective second asphericmirrors; a plurality of light receivers that includes filters of aplurality of different light colors each having a wavelength longer thanthat of the blue light, in a light-receiving area where the light beamsfrom the second mirrors are incident and images are thereby formedaccording to the light beams from the respective apertures; a casingwhere at least the first and second aspheric mirrors are disposed on afirst side of the casing in the secondary scan direction, and theaperture mirror is disposed on a second side thereof in the secondaryscan direction; and a low-cut filter that cuts off light wavelengthsshorter than that of blue light, provided in each path of the lightbeams passing from the respective fluorescent light sources to thedocument.

In yet still another aspect according to the present invention, an imagesensing apparatus comprises a plurality of light sources that shinesfluorescent light beams on an illumination portion of a document acrossthe entire range in a primary scan direction, a first mirror thatreceives incident light scattered by reflection from the document, toreflect the scattered light in the secondary scan direction; a pluralityof first concaved aspheric mirrors that collimates the light beams fromthe first mirror, to reflect therefrom the collimated light beams assubstantially collimated light fluxes; an aperture mirror that reflectstherefrom the light beams from the first aspheric mirrors, throughapertures each having a light-shielded portion formed therearound andselectively passing the light beams therethrough; a plurality of secondconcaved aspheric mirrors that receives the light beams incident fromthe aperture mirror, to reflect the incident light beams as converginglight beams; a second mirror that reflects the light beams in adirection perpendicular to the surface of the document, disposed on apath of the light beams to be converged by means of the respectivesecond aspheric mirrors; a plurality of light receivers that includesfilters of a plurality of different light colors each having awavelength longer than that of the blue light, in a light receiving areawhere the light beams from the second mirrors are incident and imagesare thereby formed according to the light beam from the apertures; acasing where at least the first and second aspheric mirrors are arrangedin respective arrays on a first side of the casing in the secondary scandirection, along the primary scan direction and the apertures and theaperture mirror are disposed in respective arrays on a second sidethereof in the secondary scan direction, therealong; and a low-cutfilter that cuts off light wavelengths shorter than that of blue light,provided in each path of the light beams passing from the respectivefluorescent light sources to the document.

In the image sensing apparatus according to the present invention, acompact image sensing apparatus can be provided by repeatedlyreflecting, in an alternate direction, light beams in the casing even ina long optical path, notwithstanding the subject-to-camera distance isdeep. In the image sensing apparatus according to the present invention,arrangement in an array of multiple second aspheric mirrors can achievean image sensing apparatus with a long sensing path.

These and other objects of the present invention will be betterunderstood by reading the following detailed description in combinationwith the attached drawings of a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an internal view of an image sensing apparatus in accordancewith Embodiment 1 of the present invention;

FIG. 2 is a schematic diagram of a configuration of an optical lenssystem in the image sensing apparatus and a cross-sectional view takenalong line X-X, in accordance with Embodiment 1 of the presentinvention;

FIG. 3 is a schematic diagram illustrating an optical mirror system ofan image sensing apparatus in accordance with Embodiment 1 of thepresent invention;

FIG. 4 is a plan view of the image sensing apparatus in accordance withEmbodiment 1 of the present invention;

FIG. 5 is a plan view of a sensor substrate in accordance withEmbodiment 1 of the present invention;

FIG. 6 is a plan view and a side view of an image sensor integratedcircuit chip in accordance with Embodiment 1 of the present invention;

FIG. 7 is a schematic diagram for illustrating light source portionsincluding a light guide in accordance with Embodiment 1 of the presentinvention;

FIG. 8 is another schematic diagram for illustrating the light sourceportions including the light guide in accordance with Embodiment 1 ofthe present invention;

FIG. 9 is a block diagram of the image sensing apparatus in accordancewith Embodiment 1 of the present invention;

FIG. 10 is an interconnection diagram between the image sensorintegrated circuit chips of the image sensing apparatus in accordancewith Embodiment 1 of the present invention;

FIG. 11 is an interconnection diagram of another example of the imagesensor integrated circuit chips of the image sensing apparatus inaccordance with Embodiment 1 of the present invention;

FIG. 12 is a signal timing diagram of the image sensing apparatus inaccordance with Embodiment 1 of the present invention;

FIG. 13 is a schematic diagram for illustrating how light beams passthrough in the image sensing apparatus in accordance with Embodiment 1of the present invention;

FIG. 14 illustrates rearrangement of inverted image data of the imagesensing apparatus in accordance with Embodiment 1 of the presentinvention; FIG. 14A shows situations without interpolation of imageinformation and FIG. 14B shows those with the interpolation;

FIG. 15 is a schematic diagram for illustrating optical lengths in asecondary scan direction of the image sensing apparatus in accordancewith Embodiment 1 of the present invention;

FIG. 16 is a schematic diagram embodying optical paths in the secondaryscan direction of the image sensing apparatus in accordance withEmbodiment 1 of the present invention;

FIG. 17 illustrates a light shield of the image sensing apparatus inaccordance with Embodiment 1 of the present invention; FIG. 17A is anelevational view of the light shield provided on the optical lenssystem, FIG. 17B is an elevational view showing the light shield, andFIG. 17C is a view showing surface roughness of the light shield;

FIG. 18 is a sectional view of an image sensing apparatus in accordancewith Embodiment 2 of the present invention;

FIG. 19 is a plan view of the image sensing apparatus in accordance withEmbodiment 2 of the present invention;

FIG. 20 is a plan view of a sensor substrate in accordance withEmbodiment 2 of the present invention;

FIG. 21 is a schematic diagram for illustrating optical lengths in thesecondary scan direction in the image sensing apparatus in accordancewith Embodiment 2 of the present invention;

FIG. 22 is a schematic diagram illustrating light shields provided on anoptical lens system of the image sensing apparatus in accordance withEmbodiment 2 of the present invention;

FIG. 23 illustrates situations where a different LED light source isused for an image sensing apparatus in accordance with Embodiment 3 ofthe present invention; FIG. 23A is a schematic diagram illustratinglight source portions including the light guide; and FIG. 23B is aschematic diagram showing a partially enlarged portion in the vicinityof the electrode section;

FIG. 24 is a schematic diagram illustrating situations where thedifferent LED light source is used for an image sensing apparatus inaccordance with Embodiment 3 of the present invention, and showssituations where a vertical light guide is used; and

FIG. 25 is a schematic diagram illustrating situations where an LED foremitting violet light is used for an image sensing apparatus inaccordance with Embodiment 3 of the present invention, and showsrelative light outputs against each of the wavelengths, in situationswhere a cut filter for excluding emitted fluorescent light beams isprovided or not.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1

An image sensing apparatus in accordance with Embodiment 1 of thepresent invention will be described below with reference to FIG. 1. FIG.1 is a schematic diagram illustrating an internal view of the imagesensing apparatus in accordance with Embodiment 1 of the presentinvention. Referring to FIG. 1, an illuminated object (referred to as apaper sheet) such as a document or a medium, is indicated at numeral 1;a platen 2 supports the illuminated object 1; light guides 3 transmitlight beams; light-emitting portions of the light guides 3 are indicatedat numeral 3 a; the light beams pass through a light transmission member4; an illumination portion of the illuminated object 1 is indicated atnumeral 5; a first mirror 6 reflects in a secondary scan directionscattered light incident from the illumination portion 5; first concavedlens mirrors 7 (also referred to as first lenses, or first asphericmirrors) receive the light beams reflected from the first mirror 6; anaperture mirror 8 receives collimated light beams incident from thefirst lens mirror 7; second concaved lens mirrors 9 (also referred to assecond lenses, or second aspheric mirrors) receive the light beamsreflected from the aperture mirror 8; apertures 10 each having alight-shielded portion formed therearound are provided on the surface ofthe aperture mirror 8 that mitigate aberration of light beams incidentupon and reflected from the aperture mirror 8; and a second mirror 11receives the light beams from the second lenses 9 and reflects theincident light beams therefrom.

An image sensor MOS integrated circuit chip 12, constituted of anopto-electric conversion circuit and its drive section, receives via thesecond mirror 11 light beams reflected from the second lenses 9; asensor substrate 13 mounts the image sensor integrated circuit chip 12thereon; a signal processing integrated circuit (ASIC) 14 processesopto-electrically converted signals; components 15 such as capacitorsand resistors are mounted on the image sensor substrate 13; and a casing16 houses the optical system including the image sensor substrate 13.

FIG. 2 is a schematic diagram illustrating an optical lens systemdisposed in an array with a 6 mm pitch, mounted on the image sensingapparatus in accordance with Embodiment 1 of the present invention; alens mount 17 integrally disposes the first lenses 7 and second lenses9; and a light shield 18 protects light interference occurring betweenthe first lenses 7 and the second lenses 9 each disposed in an array onthe lens mount 17. The lens mount 17, the first lens 7 and the secondlens 9 are made of acrylic resin, being coated with a black shieldingsubstance except for lens mirror surfaces. The lens mount 17, the firstlens 7 and the second lens 9 may be integrally formed with acrylicresin. In the figures, like reference numerals as in FIG. 1 indicatelike parts or corresponding portions.

FIG. 3 is a schematic diagram of the optical mirror system; the firstmirror 6 and second mirror 11 are continuously disposed longitudinallyso that both mirrors are located opposite each other with the aperturemirror 8 therebetween. The surface of the aperture mirror 8, made ofblack resin or sheet metal, is provided in an array with openings spacedapart at 6 mm intervals. In the figures, like reference numerals as inFIG. 1 indicate like parts or corresponding portions.

FIG. 4 is a plan view of the image sensing apparatus in accordance withEmbodiment 1 of the present invention; a light source 19 emits lightinto the light guide 3; and a connector 20 provides an I/O interfacethrough which control signals that drives the image sensing apparatusare delivered.

FIG. 5 is a plan view of a sensor substrate 13; a light sourceconnection section 19 a electrically connects the light source 19 to theconnector 20 of the sensor substrate 13.

FIG. 6 is a plan view of the image sensor integrated circuit chip 12;The light receiving surface of a light receiving section 21 (a cell) isprovided with an RGB filter made of a substance such as gelatin of red,green and blue lights for each pixel; an opto-electrical conversion andRGB shift register drive circuit 22 opto-electrically converts on an RGBbasis the light beam incident on the cell 21, and retains theirelectrical outputs, to drive the shift register; and a wire bonding pad24 inputs or outputs signals and receives or supplies electrical power,to the sensor integrated circuit chip 12 therethrough.

FIG. 7 is a schematic diagram for illustrating light source portionsincluding the light guide 3; a light scatter layer 25 uniformly shinethe light beam across the entire range in a primary scan direction fromthe light emitting section 3 a of the light guide 3; electrode sections26 are disposed at both ends of the light guide 3; light sources 27 areconstituted by light emitting diodes (LED chip array) each emitting ared, green or blue wavelength light beam. As shown in FIG. 8, each ofthe electrode sections 26 is provided with an R light source (27R), a Blight source (27B) and a G light source (27G). When the light sources 27each are disposed on both ends of the light guide 3, the width of thelight scatter layer 25 is made greater at its midsection in a primaryscan direction—i.e., a direction along the longitudinal axis of theapparatus, while when disposed on one end, the light layer width is madegreater as the light sources 27 recedes, thus ensuring uniform lightemission from a light-emitting section 3 a.

Here, the optical wavelength of each of the RGB light sources 27 issubstantially coincident with that of light of each color of the RGBfilters provided on the light receiving section 21. In FIGS. 4 through7, like reference numerals as in FIG. 1 indicate like parts orcorresponding portions. FIG. 9 is a block diagram illustrating the imagesensing apparatus according to Embodiment 1; an amplifier 30 amplifies asignal opto-electrically converted with the sensor integrated circuitchip 12; an analog-digital converter (an A/D converter) 31 performsanalog-digital conversion of the amplified opto-electrical conversionoutput; a signal processing section 32 performs signal processing ofdigitized output signals for each RGB component; a system interfacecircuit 33 allows for signal/data transfers between an image sensingapparatus (also referred to as CIS, contact image sensor) and the mainsystem; and a random-access memory (RAM) 34 stores image information foreach color. A CPU is indicated at numeral 35; a light source drivecircuit is indicated at numeral 36.

Next, the operation of the image sensing apparatus in accordance withEmbodiment 1 of the present invention will be described below. Withreference to FIG. 9, based on a system control signal (SYC) and a systemclock signal (SCLK) delivered from the main system, a clock signal (CLK)of the signal processing integrated circuit (ASIC) 14 and a start signal(SI) synchronized with the CLK are outputted via the system interfacecircuit 33 to the sensor integrated circuit chip 12. With the timing,the sensor integrated circuit chip 12 outputs sequential analog signalsof each pixel (n) for each sensing line (m). FIG. 10 exemplifies thatthe analog signal for 7200 pixels is outputted sequentially, while FIG.11 illustrates that each 144 pixel signal is outputted as a unit of asegmented output signal.

Analog signals amplified with the amplifier 30 are converted with theA/D converter 31 into digital signals; after the A/D conversion, thesignal output for each pixel (bit) is processed in a correction circuitthat performs a shading correction or all-bit correction. Thiscorrection is made by the following processes: first, signal data arepre-read using a standard test chart such as a white paper sheet; next,correction data by equalization is stored in the RAM 34; then thecorrection data is read out from the RAM 34; and finally, digitalsignals corresponding to A/D converted image information is processedarithmetically. Such sequential actions are controlled by the CPU 35.The correction data is intended to correct variations of sensitivitybetween elements of the sensor integrated circuit chip 12, ordisuniformities of the respective light sources 27.

Next, a drive timing of the image sensing apparatus in accordance withEmbodiment 1 of the present invention will be described with referenceto FIGS. 9 and 12. Referring to FIGS. 9 and 12, the ASIC 14 turns ON alight-source-on-signal with the CPU 35 interfaced therewith; in responseto this, the light source drive circuit 36 supplies the power to each ofthe light sources 27 for a predetermined time, thus causing the RGBlight sources 27 to emit white light. In synchronization with thecontinuously generated CLK signal, the start signal (SI) sequentiallyturns ON a shift register output from each element (pixel) thatconfigures the RGB drive circuit in the sensor integrated circuit chip12. A group of corresponding switches sequentially open and close theSIG (SO) lines, thereby acquiring the RGB image information (imageoutput data) synchronized with the CLK signal. This image output is eachimage output data read and stored in the previous line. Here, a CNTsignal is a color/monochrome switching signal, and typically, the colormode signal is set to a high level. A blanking (BLK) time is assigned toeach color sensing period of a single line, thus varying a setting ofexposure time; accordingly, all the SIG(SO) are left open during eachBLK interval.

Next, the sequentially outputted image signal SIG (SO) will be describedwith reference to FIG. 13. FIG. 13 is a schematic diagram forillustrating how light beams in the primary scan direction pass throughin the image sensing apparatus; the illumination portion 5 varies, inthe direction perpendicular to the carriage surface, according to thethickness of the illuminated object 1; When a point light source isassumed on the surface of the object 1, scattered light, i.e., imageinformation of the illuminated object 1 enters, via the first mirrorthat reflects the light beams in the secondary scan direction, the firstconcaved aspheric mirrors that each collimate the scattered light beamsto thereby reflect them as substantially collimated light fluxes. Thelight beams from each optical system arranged in an array are focused onapertures (openings) placed discretely with 6 mm intervals; Furthermore,the light beams emitted from the openings enter the sensor integratedcircuit chip 12 for each light flux, via lenses fitted with the lightshields 18 that each protect light interference for each array; as aresult, image information is focused as an inverted image on thelight-receiving surface of the sensor integrated circuit chip 12. Thus,the image information, focused on the light receiving portion (alsoreferred to as pixels) of the sensor integrated circuit chip 12, isdisplayed as an inverted image with respect to the illuminated object 1such as a paper sheet. By shift-register sequential switching signalsdelivered to the drive circuit of the sensor integrated circuit chip 12,the SIG (SO) signals as analog signals are concurrently outputted inthree lines for each RGB signal.

FIG. 14 illustrates rearrangement of inverted image data of the A/Dconverted RGB signals; FIG. 14A shows rearrangement of the data for each144 bits. In FIG. 14A, each of the RGB (SO) signals is processed asfollows: data shifted leftward in a shift register circuit is stored ineach cell configured by a shift register circuit, and then the data arelatched with a latch signal (LA); subsequently, the RAM 34 stores data,as SIG (SO) signals, that are sequentially rearranged with a writesignal (WR) starting with the first cell of the sensor integratedcircuit chip 12, then the stored data are corrected by computing.

FIG. 14B illustrates an example where there is a need for virtual bits(elements) generated between the light receiving portions 21 disposed inthe outermost position of the sensor integrated circuits 12; the virtualbit data is transferred to the RAM 34, with a data address added theretoas simply averaged outermost position data. In this case, the RAM 34also stores data that preliminarily incorporates the virtual bits, thusprocessing arithmetically to correct the stored data. The image datathus corrected by computing are outputted as SIG (RGB) color data, viathe system interface circuit 33, by means of color conversion, colormanagement engine and the like, through a color management systemincluding data analysis and data recovery, as is disclosed in JapaneseUnexamined Patent Publication H8-28966 (FIG. 1).

FIG. 15 is a schematic diagram illustrating optical lengths in thesecondary scan direction; the position of the first focal point of therespective first lenses 7 is substantially coincident with the variableillumination portion 5 of the illuminated object 1, while the positionof the second focal point thereof is coincident with that of theaperture mirror 8. The position of the first focal point of the secondlenses 9 is coincident with the aperture mirror 8, while the position ofthe second focal point thereof is coincident with the light receivingsurface. In other words, the following relationships hold: L3=L1+L2,L4=L5+L6, and L3=L4+B, as are shown in FIG. 16. FIG. 16 embodies opticalpaths in the secondary scan direction; Substantially collimated lightbeams travel optical distances L3 and L4 from the first lens 7 to thesecond lens 9. It should be noted that the scattered light to bereflected from the first mirror in the secondary scan direction may beemitted in any direction toward the mirror, and the light receivingportion 21 may be located in an arbitrary position as long as therelationship L4=L5+L6 is satisfied.

FIG. 17 illustrates the light shields 18 to be provided on the firstlenses 7 and second lenses 9 that are integrally configured. In FIG.17A, each of grooves (grooved portions) of the lens holder stand 17,indicated at numeral 17 a, is provided between the lenses each arrangedin an array. Fitting each of the light shields 18 into the respectivegrooves 17 a protects a light beam from leaking largely to theneighboring second lenses 9. FIG. 17B is a partially enlarged view ofthe respective light shields 18; the surfaces of the light shields 18each having a thickness of 0.3 mm, made of carbon glass material, aresandblasted or etched, and roughed to approximately 0.02 mm peak to peakas illustrated in FIG. 17C. Such surface treatment completely absorbsunwanted light beams that enter in the proximity of both ends of thesecond lenses 9 in the primary scan direction and are reflected by thelight shields 18. In addition, when reflectance, albeit in black color,is 15-20% by roughing the surface of acrylic resin throughvapor-deposition of black nitride film substance, a ghost phenomenon ingenerated images can be reduced structurally (hardware-wise).

From the foregoing description, in the image sensing apparatus inaccordance with Embodiment 1 of the present invention, the aperturemirror to reflect the light beams incident from the first asphericmirrors, the second concaved aspheric mirrors that receive the lightbeam incident from the aperture mirror, to reflect the incident lightbeams as converging light beams, are disposed on a first side of thecasing in the secondary scan direction, and the aperture mirror isdisposed on the second side thereof in the secondary scan direction; asa result, a compact image sensing apparatus can be provided byreflecting light beams inside the casing even in a long optical path,notwithstanding the depth of field is deep.

In addition, the RGB light color is used for the respective lightsources 27, RGB filters corresponding to the RGB light color from thelight sources 27 are used on the light-receiving side, and additionally,the surfaces of the light-absorbing black light shields 18 are roughed;thus, in comparison with a light source having a wide wavelength such asin a fluorescent lamp, sharp and high quality image information beingghost-free images and matching with dropout colors can be achieved.

Embodiment 2

As has been described in Embodiment 1, the light beams from both-endlight sources are shone on the illuminated object 1 by using therod-like light guides 3, while in Embodiment 2, an array light source isused, as will be described below. FIG. 18 is a schematic diagramillustrating a cross-sectional view of the image sensing apparatus inaccordance with Embodiment 2 of the present invention. In FIG. 18, avertical light guide 130 transmits a light beam; a light-emittingportion of the light guide 130 is indicated at numeral 130 a. A cover140 is comprised of a plastic material having a slit, through which thelight beams pass, in the neighborhood of the illumination portion 5 andconstitutes part of a carriage path of the illuminated object 1; a firstmirror 160 reflects scattered light incident from the illuminationportion 5; first concaved lens mirrors 170 (first lenses) each receivethe light beams reflected from the first mirror 160; an aperture mirror180 receives collimated light beams incident from the first lens mirrors170; and second concaved lens mirrors 190 (second lenses) receive thelight beams reflected from the aperture mirror 180.

A second mirror 200 receives the light beams from the second lenses 190and reflects the incident light beams therefrom; a sensor substrate 201mounts the image sensor integrated circuit chips 12 and the lightsources 27 thereon in respective arrays; a casing 202 houses the opticalsystem including the image sensor substrate 201. A holder stand 202 a ofthe light guide 130 constitutes part of the casing 200; pulleys(carriage pulleys) 203 carry the illuminated object 1. In the figures,like reference numerals as in FIG. 1 indicate like parts orcorresponding portions.

FIG. 19 is a plan view illustrating the image sensing apparatus inaccordance with Embodiment 2 of the present invention; a slit portion140 a of the cover 140 is provided in the sensing area in the primaryscan direction.

FIG. 20 is a plan view of a sensor substrate 201. Each of the lightsources 27 is constituted by RGB color LED chips that are sequentiallydisposed in both end portions in the primary scan direction of thesensor substrate 201. The drive power for the respective RGB lightsources 27 is supplied through the connector 20.

FIG. 21 is a schematic diagram illustrating optical lengths in thesecondary scan direction in the image sensing apparatus in accordancewith Embodiment 2 of the present invention. The position of the firstfocal point of the respective first lenses 170 is coincident with themidsection between the platen 2 and the illuminated object 1 side of thecover 140, while the position of the second focal point thereof iscoincident with that of the aperture mirror 180. The position of thefirst focal point of the respective second lenses 190 is coincident withthe aperture mirror 180, while the second focal point position thereofis coincident with the light receiving surface. In other words, thefollowing relationships hold: L3=L1+L2, L4=L5+L6, and L3=L4+B. Here, thefirst mirror 160 and the second mirror 200 are disposed in a planenormal to the carriage surface the illuminated object 1.

FIG. 22 illustrates the light shields 18 to be provided on the firstlenses 170 and second lenses 190 that are disposed in the casing 202. InFIG. 22, grooves (grooved portions) 202 b is provided on the casing 202side, between the neighboring second lenses 190 disposed in an array.Fitting each of the light shields 18 into the grooves 202 a protectslight beams from leaking to and entering the neighboring second lenses190. As is the case with Embodiment 1, the surfaces of the light shields18 each having a thickness of 0.3 mm, made of a carbon glass material,are sandblasted or etched to provide a rough surfaces. The first lenses170 and second lenses 190 are separately made of acrylic resin, andcoated, except on lens mirror surfaces, with a black shieldingsubstance, and are adhesively fixed directly to the casing 202. Here,detailed operating description of the image sensing apparatus accordingto Embodiment 2 is omitted because the description of Embodiment 1applies to Embodiment 2.

From the foregoing description, in the image sensing apparatus inaccordance with Embodiment 2 of the present invention, a sensorsubstrate 201 is provided with the RGB light sources, a vertical lightguide 130 is used which extends from the light receiving surface to theproximity of the illumination portion 5, and a multiple of the LED chips27 are disposed in an array, whereby illuminance in the illuminatedportion 5 is significantly increased in comparison with the case ofEmbodiment 1, and an advantageous effect is achieved in high speedsensing.

It should be noted that in Embodiment 2 the light guide 130 shines lightbeams from a single side onto the illumination portion 5, however, byadding another light guide on the side of the casing 202 opposite thelight guide 130, light beams from both sides may be shone on theillumination portion 5 of the sensing surface.

Embodiment 3

In Embodiment 1 and Embodiment 2, each light source of the RGB signalsis illuminated concurrently and then image information are read; inEmbodiment 3, a different LED light source is used, as will be describedbelow. Here, detailed operating description of the image sensingapparatus according to Embodiment 3 is omitted because the descriptionof Embodiment 1 applies to Embodiment 3.

FIG. 23 is a schematic diagram illustrating light source portionsincluding the light guide. In FIG. 23A, a light scatter layer 250uniformly shines the light beams across the entire range in the primaryscan direction from the light emitting section 3 a of the light guide 3;electrode sections 260 each are disposed separately at either side ofthe light guide 3; and light sources 270 each include an LED chip thatemits a violet light wavelength of 405 nm or more.[0046] In addition,FIG. 23B is partially enlarged view of the neighborhood of the electrodesection 260 in FIG. 23A; the light source of the electrode section 260includes an LED chip array (violet light source) 270, a transparentfluorescent resin 280 that reacts with the violet light source tothereby emit fluorescent light beams, a violet light cut-off filter 290that suppresses transmission of violent light therethrough, and anelectrode 300. As is the case with Embodiment 1, the violet light source270 is constituted by three LED chips in the either end of the lightguide 3. In the figures, like reference numerals as in FIG. 1 indicatelike parts or corresponding portions.

Furthermore, FIG. 24 illustrates situations where the violet lightsources 270 are disposed in an array on the sensor substrate 201, and alight-emitting section 130 a is located in the proximity of theillumination portion 5 by providing the vertical light guide 130. InFIG. 24, a holder stand 202 a, part of the casing 202, holds the lightguide 130, as is the case with Embodiment 2. In the figures, likereference numerals as in FIGS. 18 and 23 indicate like parts orcorresponding portions.

FIG. 25 shows relative light outputs against wavelengths of each offluorescent light beams that are emitted from the fluorescent resin 280by shining the violet light source 270 on the resin 280. By introducingthe violet cut-off filter 290 into a light diffusion area of the violetlight source 270, reception of the light having a violet emitting lightwavelength range is suppressed at the light receiving portions 21 of thesensor integrated circuit chips 12, while receiving the light having ablue emitting light wavelength range is not greatly suppressed thereat;consequently, light beams containing image information can be receivedthat meet each drop color of the RGB filters added on the sensorintegrated circuit chip 12.

Here, in Embodiment 3, the violet color LED is used; however,blue-emitting light has its peak emission output at the opticalwavelength in the neighborhood of 475 nm needed for the imageinformation in color representation. Given a light wavelength beingbelow that of the blue-emitting light, an advantageous effect similar tothat provided by a violet-emitting LED is achieved by replacing theviolet cut-off filter with the low cut filter 290 for wavelength lowerthan that of the violet light. Such an effect is achieved even by usingan ultraviolet-emitting LED.

From the foregoing description, in the image sensing apparatus inaccordance with Embodiment 3 of the present invention, since the lightsource of single wavelength provides a white light by using thefluorescent light beams, color images can be reproduced without usingthe light source of a plurality of wavelengths, and the RGB filters donot need to adapt to the light source wavelengths, so that various kindsof color filters can be utilized. While the present invention has beenshown and described with reference to preferred embodiments thereof, itwill be understood by those skilled in the art that variousmodifications and the like could be made thereto without departing fromthe spirit and scope of the invention.

1. An image sensing apparatus, comprising: a light source that shines light on an illumination portion of a document across the entire range in a primary scan direction; a first mirror that receives incident light scattered by reflection from the document, to reflect the scattered light in a secondary scan direction; a plurality of first concaved aspheric mirrors that collimates light beams from the first mirror, to reflect therefrom the collimated light beams as substantially collimated light fluxes; an aperture mirror that reflects therefrom the light beams from the first aspheric mirrors, through apertures each having a light-shielded portion formed therearound and selectively passing the light beams therethrough; a plurality of second concaved aspheric mirrors that receives light beams incident from the aperture mirror, to reflect the incident light beams as converging light beams; a second mirror that reflects the light beams in a direction perpendicular to the surface of the document, disposed on a path of the light beams to be converged by means of the respective second aspheric mirrors; a plurality of light receivers each having a light-receiving area where the light beams from the second mirrors are incident, and images are thereby formed according to the light beams from the respective apertures; and a casing where at least the first and second aspheric mirrors are disposed on a first side of the casing in the secondary scan direction and the aperture mirror is disposed on a second side thereof in the secondary scan direction.
 2. An image sensing apparatus, comprising: a light source that shines light on an illumination portion of a document across the entire range in a primary scan direction; a first mirror that receives incident light scattered by reflection from the document, to reflect the scattered light in a secondary scan direction; a plurality of first concaved aspheric mirrors that collimates the light beams from the first mirror, to reflect therefrom the collimated light beams as substantially collimated light fluxes; an aperture mirror that reflects therefrom the light beams from the first aspheric mirrors, through apertures each having a light-shielded portion formed therearound and selectively passing the light beams therethrough; a plurality of second concaved aspheric mirrors that receives the light beams incident from the aperture mirror, to reflect the incident light beams as converging light beams; a second mirror that reflects the light beams in a direction perpendicular to the surface of the document, disposed on a path of the light beams to be converged by means of the respective second aspheric mirrors; a plurality of light receivers each having a light-receiving area where the light beams from the second mirrors are incident and images are thereby formed according to the light beams from the respective apertures; and a casing where at least the first and second aspheric mirrors are arranged in respective arrays on a first side of the casing in the secondary scan direction, along the primary scan direction and the apertures and the aperture mirror is arranged in respective arrays on a second side thereof in the secondary scan direction, therealong.
 3. The image sensing apparatus of claim 1, wherein the aperture mirror is located at focal point of the respective first aspheric mirrors.
 4. The image sensing apparatus of claim 1, wherein the aperture mirror is located at focal point of the respective second aspheric mirrors.
 5. The image sensing apparatus of claim 1, wherein the first aspheric mirrors are integral with the second aspheric mirrors, and the first ones are located to the side of the illumination portion and the second ones to the side of the light receiver.
 6. The image sensing apparatus of claim 1, wherein a plurality of light shields that each prevents leak light incident on any one of the second aspheric mirrors arranged in an array from its neighboring mirrors is provided in boundary regions of the mirrors.
 7. The image sensing apparatus of claim 6, wherein each of the light shields has an uneven surface.
 8. The image sensing apparatus of claim 1, wherein the first and second mirrors are disposed in a plane normal to a carriage plane of an illuminated object.
 9. An image sensing apparatus, comprising: an RGB light source that shines light on an illumination portion of a document across the entire range in a primary scan direction; a first mirror that receives incident light scattered by reflection from the document, to reflect the scattered light in a secondary scan direction; a plurality of first concaved aspheric mirrors that collimates light beams from the first mirror, to reflect therefrom the collimated light beams as substantially collimated light fluxes; an aperture mirror that reflects therefrom the light beams from the first aspheric mirrors, through apertures each having a light-shielded portion formed therearound and selectively passing the light beams therethrough; a plurality of second concaved aspheric mirrors that receives light beams incident from the aperture mirror, to reflect the incident light beams as converging light beams; a second mirror that reflects the light beams in a direction perpendicular to the surface of the document, disposed on a path of the light beams to be converged by means of the respective second aspheric mirrors; a plurality of light receivers each having RGB filters corresponding to the respective optical wavelengths of the RGB light beams in a light-receiving area where the light beams from the second mirrors are incident and images are thereby formed according to the light beams from the respective apertures; and a casing where at least the first and second aspheric mirrors are disposed on a first side of the casing in the secondary scan direction and the aperture mirror is disposed on a second side thereof in the secondary scan direction;
 10. An image sensing apparatus, comprising: an RGB light source that shines light on an illumination portion of a document across the entire range in a primary scan direction; a first mirror that receives incident light scattered by reflection from the document, to reflect the scattered light in a secondary scan direction; a plurality of first concaved aspheric mirrors that collimates light beams from the first mirror, to reflect therefrom the collimated light beams as substantially collimated light fluxes; an aperture mirror that reflects therefrom the light beams from the first aspheric mirrors, through apertures each having a light-shielded portion formed therearound and selectively passing the light beams therethrough; a plurality of second concaved aspheric mirrors that receives light beams incident from the aperture mirror, to reflect the incident light beams as converging light beams; a second mirror that reflects the light beams in a direction perpendicular to the surface of the document, disposed on a path of the light beams to be converged by means of the respective second aspheric mirrors; a plurality of light receivers each having RGB filters corresponding to the respective optical wavelengths of the RGB light beams in a light-receiving area where the light beams from the second mirrors are incident and images are thereby formed according to the light beams from the respective apertures; and a casing where at least the first and second aspheric mirrors are arranged in respective arrays on a first side of the casing in the secondary scan direction, along the primary scan direction and the apertures and the aperture mirror are arranged in an array on a second side thereof in the secondary scan direction, therealong.
 11. The image sensing apparatus of claim 10, wherein a plurality of light shields that each prevents leak light incident on any one of the second aspheric mirrors arranged in an array from its neighboring mirrors is provided in boundary regions of the mirrors.
 12. The image sensing apparatus of claim 11, wherein each of the light shields has an uneven surface.
 13. An image sensing apparatus, comprising: a fluorescent light source that shines fluorescent light on an illumination portion of a document across the entire range in a primary scan direction; a first mirror that receives incident light scattered by reflection from the document, to reflect the scattered light in a secondary scan direction; a plurality of first concaved aspheric mirrors that collimates light beams from the first mirror, to reflect therefrom the collimated light beams as substantially collimated light fluxes; an aperture mirror that reflects therefrom the light beams from the first aspheric mirrors, through apertures each having a light-shielded portion formed therearound and selectively passing the light beams therethrough; a plurality of second concaved aspheric mirrors that receives the light beams incident from the aperture mirror, to reflect the incident light beams as converging light beams; a second mirror that reflects the light beams in a direction perpendicular to the surface of the document, disposed on a path of the light beams to be converged by means of the respective second aspheric mirrors; a plurality of light receivers that includes filters of a plurality of different light colors each having a wavelength longer than that of the blue light, in a light-receiving area where the light beams from the second mirrors are incident and images are thereby formed according to the light beams from the respective apertures; a casing where at least the first and second aspheric mirrors are disposed on a first side of the casing in the secondary scan direction and the aperture mirror is disposed on a second side thereof in the secondary scan direction; and a low-cut filter that cuts off light of wavelengths shorter than that of blue light, provided in the path of the light passing from the fluorescent light source to the document.
 14. An image sensing apparatus, comprising: a fluorescent light source that shines fluorescent light on an illumination portion of a document across the entire range in a primary scan direction; a first mirror that receives incident light scattered by reflection from the document, to reflect the scattered light in a secondary scan direction; a plurality of first concaved aspheric mirrors that collimates light beams from the first mirror, to reflect therefrom the collimated light beams as substantially collimated light fluxes; an aperture mirror that reflects therefrom the light beams from the first aspheric mirrors, through apertures each having a light-shielded portion formed therearound and selectively passing the light beams therethrough; a plurality of second concaved aspheric mirrors that receives the light beams incident from the aperture mirror, to reflect the incident the light beams as converging light beams; a second mirror that reflects the light beams in a direction perpendicular to the surface of the document, disposed on a path of the light beams to be converged by means of the respective second aspheric mirrors; a plurality of light receivers that includes filters of a plurality of different light colors each having a wavelength longer than that of the blue light, in a light-receiving area where the light beams from the second mirrors are incident, and images are thereby formed according to the light beams from the respective apertures; a casing where at least the first and second aspheric mirrors are arranged in respective arrays on a first side of the casing in the secondary scan direction, along the primary scan direction and the apertures and the aperture mirror are arranged in respective arrays on a second side thereof in the secondary scan direction, therealong; and a low-cut filter that cuts off light of wavelengths shorter than that of blue light, provided in the path of the light passing from the fluorescent light source to the document.
 15. The image sensing apparatus of claim 14, wherein a plurality of light shields that each prevents leak light incident on any one of the second aspheric mirrors arranged in an array from its neighboring mirrors is provided in boundary regions of the mirrors.
 16. The image sensing apparatus of claim 15, wherein each of the light shields has an uneven surface. 